Quantum cascade lasers provide a tunable mid-infrared (MIR) light source that can be used for spectroscopic measurements and images. Many chemical components of interest have molecular vibrations that are excited in the MIR region of the optical spectrum, which spans wavelengths between 5 to 25 microns. Hence, measuring the absorption of MIR light or reflection of MIR light at various locations on a sample can provide useful information about the chemistry of the sample as a function of position on the sample.